Cardiovascular Research Program concerns studies of cardiac muscle and its blood supply. These studies are being performed at both a clinical and at a basic level. The mechanics and hemodynamics of cardiac muscle will be studied in intact man with particular emphasis on dynamic morphology of contraction as determined by angiographic, ultrasonographic, electrographic and isotope techniques. Blood flow to the myocardium will be studied in man and in the experimental animal, using both direct and diffusible indicator techniques. These studies will analyze both the topographic and the depth distribution of blood flow under a variety of normal and pathological conditions. Studies in coronary heart disease will include its modification by therapeutic intervention and the use of experimental vascular models.